Location: Wedding Hall, Moon Kingdom
Phase 1: Bowser attacks with fire breath, tail swipes, and by throwing his hat. Dodge his attacks. When he throws his hat, capture it and use it to attack him. Spin the hat to hit him multiple times. He'll be stunned and fall into a lava pit.
Phase 2: Bowser will emerge from the lava pit, now much larger. You'll need to capture a giant Piranha Plant. Use the Piranha Plant to spit fireballs at Bowser. Aim for his face. After taking damage, he'll retreat again.
Phase 3: Bowser will be even larger and more aggressive. Continue using the captured Piranha Plant to hit him with fireballs. After enough hits, he'll be defeated. This leads into the final escape sequence where you capture Bowser himself.
Final Escape (Captured Bowser): As captured Bowser, smash through obstacles and enemies. Use his fire breath to clear paths. The goal is to reach the end of the collapsing moon. This sequence is mostly linear but requires quick reflexes to avoid falling debris and navigate the environment. Successfully escaping completes the main story.
Reward: Multi Moon, Game Completion